- Kinetics of sTNF-R1, sTNF-R2 and sIL-2R α (concentration levels pre-/post-apheresis as well as determination of receptor levels during treatments). Soluble receptor levels will be measured in the first 3 recruited patients at day 4 to 5 (hourly for the first 3 hours, every 2 hours for the following 6 hours and every 3 hours until treatment start on day 5).